Apparatus for facilitating the extraction of minerals from the ocean floor

ABSTRACT

A method and apparatus for facilitating the extraction of valuable minerals which have settled and solidified to form a hard layer covering the floor of the ocean. The invention is based upon the employment of a high-intensity shock wave to break up the solidified material so that it may readily be brought to the surface by dredging or other conventional means. In a preferred embodiment, the shock wave is produced by creating plasma discharge between two electrodes immersed in sea water, these electrodes having been inserted into an opening formed in the material to be extracted.

United States Patent inventor Louis R. Padberg, Jr.

22 Rlncon Vista, Santa Barbara, Calif. 93103 Appl. No. 826,945

Filed May 22, 1969 Patented June 8, 1971 APPARATUS FOR FACILITATING THEEXTRACTION OF MINERALS FROM THE OCEAN FLOOR 6 Claims, 4 Drawing Figs.

lnt.Cl E21c 37/18 Field of Search 299/13, 14,

Primary ExaminerEmest R. Purser Attorneys-Edgar J. Brower, Q. BaxterWarner and Joward J.

Murray, Jr.

ABSTRACT: A method and apparatus for facilitating the extraction ofvaluable minerals which have settled and solidified to form a hard layercovering the floor of the ocean. The invention is based upon theemployment of a high-intensity shock wave to break up the solidifiedmaterial so that it may readily be brought to the surface by dredging orother conventional means. in a preferred embodiment, the shock wave isproduced by creating plasma discharge between two electrodes immersed insea water, these electrodes having been inserted into an opening formedin the material to be extracted.

M ocem SURFACE DEEP SUBMERGENCE SEARCH Kg/EHICLE PATENTEU JUN 8I8TI3583.766

sum 1 0F 2 DEEP SUBMERGENCE SEARCH I(\DIEHICLE OCEAN BED Fig. l

INVENTOR. LOUIS R. PADBERG JR.

BY AGE/VT ATTORNEY PATENIEU JUN 8 l97l 3, 5 3; 7

sum 2 or 2 ENERGIZING CIRCUIT APPARATUS FOR FACILITATING THE EXTRACTIONOF MINERALS FROM THE OCEAN FLOOR STATEMENT OF GOVERNMENT INTEREST Theinvention described herein may be manufactured and used by or for theGovernment of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION It has long been known that valuableminerals, such for example as manganese, occur in great abundance inmany places on the floor of the ocean and on the sides of sea mounts.These minerals have been deposited over long periods of time by settlingand solidification, as a result of which they are almost rocklike incharacter and hence difficult to extract by ordinary methods.

Attempts have been made to break up these deposits by chemicalexplosives such as TNT. Although such expedients do result in fracturingthe deposits to a degree, they are also hazardous to many forms ofmarine life, and their use has been strongly opposed both by the fishingindustry and by conservationists interested in protecting the earthnatural resources.

SUMMARY OF THE INVENTION It has been found that this breaking up, orfracturing, process may be more efficiently carried out and with minimumdanger to see life by generating high-intensity acoustic energy in theform of sharp pressure waves which are controllable both as to frequencyand direction in accordance with the environmental characteristics ofthe region where the operation is perfonned. In a preferred embodiment,a standard type of ocean floor drill may be utilized to make an openingin the mineral deposit of interest. In a tube above the drill may belocated an assembly consisting of a pair of electrodes between whichextends a thin wire composed of some material such as nickel. When ahigh current is suddenly applied between the electrodes, the wirevaporizes to create a plasma discharge accompanied by sharp pressurewaves. These pressure waves pass out of the tube through openings soconfigured as to focus the energy into the mineral deposit to break upthe latter. The resulting small pieces of mineral matter may thenreadily be dredged or otherwise brought to the surface.

OBJECTS OF THE INVENTION One object of the present invention, therefore,is to provide an improved method and means for dislodging mineraldeposits from the floor of the ocean or other large body of water.

A further object of the invention is to provide means for dislodgingminerals from the floor of the ocean through the electrical generationof shock waves having a level of intensity comparable to that obtainablefrom the use of chemical explosives.

An additional object of the invention is to provide means for creating aplasma discharge underwater and for directing the resulting shock wavesinto a solid mass of mineral deposits to break up the latter so that theresulting small pieces may be more readily brought to the surface.

Other objects, advantages, and novel features of the invention willbecome apparent from the following detailed description of the inventionwhen considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a schematic view, partly insection, of a preferred embodiment of the present invention, alsoshowing one manner in which the mineral-fracturing process may becarried out;

FIG. 2 is an enlarged view, partly in section, of a portion of FIG. 1,illustrating the electrical connections to the electrodes between whicha plasma discharge is created;

FIG. 3 illustrates the effect of creating such a plasma discharge; and

FIG. 4 is an enlarged view of one of the electrodes of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT ln FiG. 1 of the drawings isshown one form of apparatus embodying the principles of the presentconcept. Inasmuch as the invention contemplates the creation of a plasmadischarge into the material to be fractured, there is illustrated onemanner in which this objective may be achieved. An underwater vehicle10, which may be any suitable submersible such for example as an OceanWork Submarine or a DSSV (Deep Submergence Search Vehicle) capable ofremaining relatively motionless below the surface, is provided with alength of pipe 12 terminating in a drill head 14, the pipe 12 extendingvertically downwardly as set forth in the drawing and being capable ofextension and retraction from and into the vehicle 10 by any suitableconventional mechanism (not shown). As an alternative, the pipe 12 maybe lowered from an ocean coring or drilling vessel of the type employedin exploratory operations by the petroleum industry. The particularmethod and/or means selected to raise and lower the pipe 12 forms nopart of the present invention, however, and the choice of apparatusemployed will depend not only on the depth at which the fracturingprocess herein described is to be performed, but also upon the nature ofthe mineral deposit the extraction of which is desired.

Above the drill head 14, the drill pipe 12 is modified to include aplasma discharge section 16 shown in greater detail in FIG. 2 of thedrawings. Although the interior assembly of this section will bedescribed hereinafter, it might be mentioned at this point that theouter wall thereof is slotted or otherwise provided with a plurality ofvertically spaced openings 18 extending part way around thecircumference of the pipe section, and preferably offset from oneanother as illustrated. These openings 18 are provided for the purposeof permitting shock waves generated within the section 16 to emergetherefrom, and hence their number, size and configuration are matters ofchoice. The openings 18 may also be formed at an angle with the axis ofthe pipe 12 so as to have a directive effect on any pressure wavespassing therethrough, if such an expedient is found to be desirable.

Referring again to FIG. 1, the pipe 12 is lowered from the vehicle 10 sothat the drill head 14 forms a pilot hole 19 extending a distance ofapproximately 6 feet (for example) into the ocean floor, the depth ofthis hole being such that the pipe section 16 lies within the upper andlower boundaries of a layer 20 of mineral deposits the extraction ofwhich is desired. This mineral layer 20 overlies the sedimentary oceanbed 22. The openings 18 in the pipe section 16 are thus brought into aposition where they directly face the material to be fractured.

The present concept now contemplates the production of a plasmadischarge within the pipe section 16. This discharge is created by meansfully described in applicants U.S. Pat. No. 3,364,708 issued Jan. 23,1968 and entitled Electrical Discharge Method of and Apparatus forGenerating Shock Waves in Water. In this patent is set forth means fordischarging electrical energy through a predetermined path in water andwith such a high level of intensity and rapid rate of discharge as togenerate a rapidly expanding and collapsing gas bubble with accompanyingshock waves simulating those receivable from explosives. Although theprinciples underlying the concept of the patent will not be repeatedherein, it might be said that when extremely high' potentials areapplied across an electrode gap immersed in an electrically conductingfluid such as sea water, the ensuing electrical discharge across the gapcauses a sudden increase in in temperature of the order of thousands ofdegrees Fahrenheit. The water vaporizes to form a gaseous bubble, thelatter expanding and collapsing, whereupon another bubble forms, expandsand collapses. .This process continues as long as the electricalpotential is applied to the electrodes at a critical level. Thealternate bubble expansion and collapse causes a propagation of acousticwaves in the form of sharp pressure pulses having a steep wave front.

Referring now to FIG. 2 of the drawings, there is illustrated a pair ofelectrodes 24 and 26, each of cup-shaped configuration and so disposedin spaced-apart relation within pipe section 16 as to face one another.The spacing of these electrodes 24 and 26 is such as to embrace all ofthe pipe openings 18 therebetween. As viewed in FIG. 2, the electrode 24is in a sense inverted, while the electrode 26 is upright. Each of theelectrodes 24 and 26 is composed of electrically conductive material,and is formed with a central contact area at the bottom of the cup forrespective attachment thereto of one end of a thin wire 28 composed ofsome material, such as nickel, which will explode when a high current issuddenly passed therethrough, as from the power source 29 when themanually operable switch 30 is closed. However, in practice, thepowergenerating arrangement of U.S. iat. No. 3,364,708 constitutes amore feasible system for this purpose. FIG. 4 of the drawings brings outthe relationship between wire 28 and electrode 24.

in order to supply such current to the wire 28, the electrode 24 iselectrically insulated from the pipe 12 by a collar 31 of some suitablematerial such as rubber or plastic, while the electrode 26 is formedwith a flanged portion 32 extending into the inner wall of pipe 12 asshown. The pipe 12 forms the negative or ground end of an electricalcircuit (such as shown, for example, in FIG. 3 of U.S. Pat. No.3,364,708) while electrode 24 is connected to the positive terminal ofsuch circuit by means of the conductor 34.

With the pipe 12 being as shown in FIG. 1 so that the openings 18 insection 16 face the wall of the opening in the mineral deposit 20,sudden passage of high current through wire 28 will cause the latter toexplode, creating a large plasma discharge accompanied by shock waves.This action is illustrated schematically in FIG. 3 of the drawings. Theshock waves are effective in fracturing the mineral deposit 20 in thevicinity of the opening 19, so that the material thus broken up maysubsequently be brought to the surface by some conventional me such asdredging.

Where small deposits of minerals are involved, the abovedescribed"one-shot" system is entirely satisfactory. It is also within the scopeof the present concept to employ a number of electrode-wire assembliesof the type shown, spaced axially from one another and capable ofindependent energization to allow for fast, sequential firing withoutraising the drill head 14 from its point of maximum penetration into theocean bed.

lclaim:

1. Apparatus for facilitating the extraction of solidified minerals fromthe floor of the ocean or other body of water, said apparatuscomprising:

means for forming an opening in a solidified mass of minerals to beextracted;

a selectively energizable source of pressure waves including a pair ofelectrodes;

means for inserting said source of pressure waves into said opening; and

means, including means for producing a plasma discharge between saidpair of electrodes, for selectively energizing said source to producepressure waves,

said waves acting to break up the solidified mineral mass in thevicinity of said opening so that the subsequent extraction of saidminerals is facilitated.

2. Apparatus according to claim 1, in which said means for producing aplasma discharge between said electrodes includes an explodable wireinterconnecting said electrodes and extending therebetween.

3. Apparatus according to claim 2, in which said means for forming anopening in a solidified mass of minerals to be extracted includes avertically positioned drill pipe having a drill head on the lower endthereof.

4. Apparatus according to claim 3, in which said pair of electrodes arelocated within said drill pipe, the latter having a plurality of sideopenings therein in the region occupied by said electrodes.

5. Apparatus according to claim 4, In which one of said pair

1. Apparatus for facilitating the extraction of solidified minerals fromthe floor of the ocean or other body of water, said apparatuscomprising: means for forming an opening in a solidified mass ofminerals to be extracted; a selectively energizable source of pressurewaves including a pair oF electrodes; means for inserting said source ofpressure waves into said opening; and means, including means forproducing a plasma discharge between said pair of electrodes, forselectively energizing said source to produce pressure waves, said wavesacting to break up the solidified mineral mass in the vicinity of saidopening so that the subsequent extraction of said minerals isfacilitated.
 2. Apparatus according to claim 1, in which said means forproducing a plasma discharge between said electrodes includes anexplodable wire interconnecting said electrodes and extendingtherebetween.
 3. Apparatus according to claim 2, in which said means forforming an opening in a solidified mass of minerals to be extractedincludes a vertically positioned drill pipe having a drill head on thelower end thereof.
 4. Apparatus according to claim 3, in which said pairof electrodes are located within said drill pipe, the latter having aplurality of side openings therein in the region occupied by saidelectrodes.
 5. Apparatus according to claim 4, in which one of said pairof electrodes is electrically connected to said drill pipe, so that thelatter forms part of said means for producing a plasma discharge betweensaid electrodes.
 6. Apparatus according to claim 5, in which each ofsaid pair of electrodes is essentially cup-shaped, the two electrodesbeing disposed in face-to-face relationship within said drill pipe, andwith the said explodable wire extending between points within therespective electrode cup portions.